Recently, an induction-heating cooking device is a target of attention as a safe heating cooking device. Conventionally, this type of induction-heating cooking device generally represents its heating state with a display section, which is provided in the vicinity of an output setting section and lit up with, for example, a light bulb or a semiconductor device. Some built-in type induction-heating cooking devices, in which the output setting section and the cooking section are visually separated from each other, have another similar display section on a front part of the cooking section. Hereinafter, a structure of a conventional induction-heating cooking device 3600 will be described with reference to FIG. 36.
As shown in FIG. 36, the induction-heating cooking device 3600 includes a case 6001 forming a main body, a cooking board 6003 on which a cooking container 6002 to be heated is to be placed, a heating coil 6004 located below the cooking board 6003, a temperature sensor 6005 for sensing the temperature of the cooking container 6002, an output control section 6006 for controlling an output of the heating coil 6004, a ventilator 6007 for cooling the output control section 6006, a power switch 6008 for turning on/off the power, a power display section 6009 for displaying the on/off state of the power switch 6008, an output setting section 6010 for setting the output, an output display section 6011 for displaying the setting state of the output, a second output display section 6012 located in a front area of the cooking board 6003, and a heating state display section 6013 for displaying the heating state.
The induction-heating cooking device having the above-described structure operates as follows. When the power switch 6008 is turned on, the power display section 6009 is lit up so as to display the on/off state of the power switch. When the cooking container 6002 accommodating food to be cooked is placed on the cooking board 6003 and the output setting section 6010 is turned on, the output display section 6011 is lit up so as to display the setting state of the output and also start heating. Simultaneously, the second output display section 6012 is lit up so as to display the setting state of the output. In accordance with the temperature sensed by the temperature sensor 6005, the heating state display section 6013 is lit up so as to display the heating state.
Conventionally, this type of induction-heating cooking device does not generate a flame and have a high thermal efficiency, unlike a gas cooking stove. Therefore, the demand for this type of induction-heating cooking device is increasing. FIG. 37 is an isometric view of a conventional, general induction-heating cooking device 3700. In FIG. 37, reference numeral 6101 represents a main body case, reference numeral 6102 represents a cooking board on which a cooking container to be heated is to be placed, reference numerals 6103 and 6104 represent heating sections using induction heating of the same rated outputs and corresponding to heating coils (not shown) provided below the cooking board 6102. Reference numeral 6105 represents a radiation heater used for heating an aluminum pan or a copper pan which cannot be heated by induction heating.
For performing induction-heating cooking using the induction-heating cooking device 3700 having the above-described structure, a cooking container which can be induction-heated is placed on the heating section 6103 or 6104 of the cooking board and the power is turned on.
An induction-heating cooking device performs cooking as follows. A high frequency electric current is caused to flow to a heating coil so as to generate a high frequency magnetic field. A Joule heat by an eddy current is generated in a pan (load) which is magnetically coupled to the heating coil, so as to heat the pan itself. Therefore, there is a problem in that the user cannot easily recognize the heating state visually, unlike with a gas cooking device generating a flame or an electric heater in which the heating section is heated red.
In order to solve this problem, for example, an induction-heating cooking device described in Japanese Patent No. 2903561 is proposed. With reference to FIG. 38, a conventional induction-heating cooking device 3800 will be described. As shown in FIG. 38, the induction-heating cooking device 3800 includes a heating coil 6202 for heating a pan located below a cooking board 6201 by induction heating, and light bulbs 6203 provided in the vicinity of the heating coil 6202. Japanese Patent No. 2903561 discloses that (i) simultaneously with a heating operation, the light bulbs 6203 provided in the vicinity of the heating coil 6202 are lit up so as to display a heating area; and (ii) when a substance which generates light when receiving light is caused to adhere to a bottom surface of an iron plate provided on a top surface of the main body, a pan is put in place and a heating operation is started, the light bulb 6203 provided at the center of the heating coil emits light; and upon receiving the light, the substance secondarily emits light, resulting in a circle 6204 as shown in FIG. 39 being displayed on the cooking board.
Japanese Laid-Open Publication No. 7-312279 describes the following. A plurality of light emitting diodes for displaying the heating state are provided along an outer periphery of the heating coil, and a light emitting diode for displaying the heating power is provided in the vicinity of and outside the plurality of light emitting diodes. When the heating coil is electrically conducted so as to be heated, the light emitting diodes for displaying the heating state are lit up. Thus, the heating state is notified. The light emitting diode provided in the vicinity thereof for displaying the heating is lit up. Thus, the heating power is clearly indicated.
With reference to FIG. 40, an induction-heating cooking device 4000 includes a heating coil 6302 for heating a pan provided below a cooking board 6301 by induction heating, and light bulbs 6303 provided in the vicinity of the heating coil 6302. Simultaneously with a heating operation, the light bulbs 6303 provided in the vicinity of the heating coil 6302 are lit up so as to display heating area.
With reference to FIG. 41, it is proposed to provide, below the heating coil, a circularly annular conductor 6304 formed by assembling a plurality of blocks, each including a conductor piece 6304a and a light source 6305. According to this structure, the plurality of light sources 6305 are provided at the center of the circularly annular conductor. When the heating coil is electrically conducted to be heated, the light sources 6305 are lit up along an outer periphery of the circularly annular conductors 6304. In this manner, the heating state is indicated.
According to the conventional method, as shown in FIG. 36, of displaying the heating state of the induction-heating cooking device 3600, the section for actually performing cooking and the section for displaying are visually separated from each other. Therefore, it is difficult for the user to visually recognize the heating state.
The induction-heating cooking device, which outputs invisible alternate magnetic fluxes, has a specific problem of being difficult to handle since it is difficult for the user to visually recognize the heating state, unlike with a gas cooking device generating a visible flame.
With induction-heating cooking devices, the user cannot visually recognize the heating state. Therefore, for safety, heating is generally started after the power is turned on, a cooking container is placed on the cooking board, and the heating power is set. As described with reference to the conventional examples, various methods have been proposed for allowing the user to visually recognize whether heating is performed or not. However, the on/off state of the power has not been much considered. Even when the cooking container is placed on the cooking board, it is not shown whether the power is on or off. Therefore, the user needs to check with the power display section each time. However, the power display section is small and far from the heating section for heating the cooking container. Thus, it is troublesome to check from time to time when the user is busy or continuously cooking.
The plurality of heating sections in the conventional induction-heating cooking device 3700 shown in FIG. 37 all use the heating coils of the same rating. For example, in FIG. 37, there are two heating sections (the heating sections 6103 and 6104). The heating coils corresponding to them both have a rated output of 2 kW.
As a wider variety of foods have become cooked in a wider variety of manners recently, there is a demand for heating sections having different outputs, especially large outputs. The present invention provides an induction-heating cooking device including heating coils having different ratings, i.e., heating sections having different inputs and outputs.
Even if the heating sections have different outputs, the difference cannot be represented with an induction-heating cooking device. In conventional induction-heating cooking devices, it does not matter which one of the heating sections is used for which cooking container. This is true when cooking containers are placed on both the heating sections, or even when one cooking container is placed on one of the heating sections.
When the heating sections have different outputs, a wrong selection of the heating section results in the cooking time being different from the expected time or the cooking being finished in a poor state due to an excessive temperature rise.
The conventional induction-heating cooking device 3800 shown in FIG. 38 includes light emitting means, for example, light bulbs 6203 in the vicinity of the heating coils 6202. This structure requires a plurality of light bulbs for displaying the heating sections corresponding to the heating coils 6202. When the number of light bulbs is limited, the heating section is difficult to see since the display is provided by dots.
A display method utilizing secondary light emission, which allows geometrical figures, such as circles, to be drawn relatively easily, has not been put into practice due to the following problems: (i) the display is faint and difficult to see due to the poor efficiency of the secondary light emission; (ii) a clear geometrical figure is difficult to draw due to the directivity or attaching dispersion of the light bulb 6203 used for light emission which are provided at the center of the heating coil; and (iii) the stability is poor since the secondary light emitting substance is provided below the cooking board 6201 having a high temperature.
The structures shown in FIGS. 40 and 41 both use a plurality of light sources. The structure is a one-system structure in which all the plurality of light sources are connected in series. Therefore, if even a part thereof malfunctions, the entire system remains unlit, which prevents the user from visually recognizing the heating section.
The pattern is limited to two: (i) lighting-up and (ii) blinking. Thus, it is impossible to provide various manners of display.
An objective of the present invention is to provide a highly safe induction-heating cooking device having an improved ease of handling by allowing a heating state to be displayed in a similar manner to that of a gas cooking device.
Another aspect of the present invention is to provide an induction-heating cooking device which allows the on/off state of the power to be easily checked and also allows whether the heating is performed or not to be easily checked.
Still another aspect of the present invention is to provide an induction-heating cooking device which allows a difference in outputs to be recognized with a simple structure.
Still another aspect of the present invention is to provide an induction-heating cooking device which can clearly display the heating area and its vicinity of the heating section corresponding to the heating coil with a small number of light sources.
Still another aspect of the present invention is to provide an induction-heating cooking device which allows the heating section to be visually recognized by preventing the entirety of a heating section from failing lighting up even if a part of the heating section malfunctions, and which allows various patterns to be provided.